CA1116409A - Process for recovery of niobium values for use in preparing niobium alloy products - Google Patents
Process for recovery of niobium values for use in preparing niobium alloy productsInfo
- Publication number
- CA1116409A CA1116409A CA000324930A CA324930A CA1116409A CA 1116409 A CA1116409 A CA 1116409A CA 000324930 A CA000324930 A CA 000324930A CA 324930 A CA324930 A CA 324930A CA 1116409 A CA1116409 A CA 1116409A
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- Prior art keywords
- niobium
- process according
- nickel
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- nbo2f
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Classifications
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G33/00—Compounds of niobium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B34/00—Obtaining refractory metals
- C22B34/20—Obtaining niobium, tantalum or vanadium
- C22B34/24—Obtaining niobium or tantalum
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
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- Inorganic Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE The invention disclosed provides a process for recover-ing niobium values from aqueous hydrofluoric acid solutions by evaporating said solution to dryness and baking the residue at temperatures of 150° to 250°C. The solid residue is niobium oxyfluoride (NbO2F) which may then be exothermically reduced with aluminum in the presence of an alloying element such as iron, nickel, or chromium to produce a niobium alloy. The eva-porated hydrofluoric acid may be recovered by condensing or absorbing the evolved vapors.
Description
g~ ~
10 ¦ FIELD OF T~IE INVENTION
11 ¦ The present invention relates to a process for the 12 ¦ aluminothermic reductïon of niobium oxyfluoride in the presence 13 ¦ of an alloying metal powder. The niobium oxyfluoride is pre-14 ¦ pared by evaporating a hydrofluoric acid solution o~f niobium 15¦ to dryness and baking at 150~C. or greater.
16¦ BACKGROUND OF THE INVENTION
17¦ This invention relates to the treatment of aqueous 18¦ hydrofluoric acid solutions of niobium emanating from the liquid-~91 liquid extraction and purification of niobium.
20¦ The usual purification and recovery of niobium from its 2i¦ ores involves taking the ore into hydrofluoric acid solution 22¦ and separating the niobium from tantalum and gangue materials by 231 its differential solubility in organic extractants such as 24 methyl-isobutyl-ketone, di-alkyl-phosphate, tributyl-phosphate, trioctyl-amine and the like. The niobium fluoride loaded organic 26 phase is then contacted with water whereby the niobium values are 27 preferentially soluble in the aqueous phase. This aqueous niobiun 28 fluoride solution is then txeated with ammonia to precipitate 29 the niobium as the hydroxide along with chemisorbed ammonium 30~ fluoride. This slurry is then Eiltered thus separating the . .
1~ ?YI
1 ammoni~m fluoride solution from the pr~cipitated niobium
10 ¦ FIELD OF T~IE INVENTION
11 ¦ The present invention relates to a process for the 12 ¦ aluminothermic reductïon of niobium oxyfluoride in the presence 13 ¦ of an alloying metal powder. The niobium oxyfluoride is pre-14 ¦ pared by evaporating a hydrofluoric acid solution o~f niobium 15¦ to dryness and baking at 150~C. or greater.
16¦ BACKGROUND OF THE INVENTION
17¦ This invention relates to the treatment of aqueous 18¦ hydrofluoric acid solutions of niobium emanating from the liquid-~91 liquid extraction and purification of niobium.
20¦ The usual purification and recovery of niobium from its 2i¦ ores involves taking the ore into hydrofluoric acid solution 22¦ and separating the niobium from tantalum and gangue materials by 231 its differential solubility in organic extractants such as 24 methyl-isobutyl-ketone, di-alkyl-phosphate, tributyl-phosphate, trioctyl-amine and the like. The niobium fluoride loaded organic 26 phase is then contacted with water whereby the niobium values are 27 preferentially soluble in the aqueous phase. This aqueous niobiun 28 fluoride solution is then txeated with ammonia to precipitate 29 the niobium as the hydroxide along with chemisorbed ammonium 30~ fluoride. This slurry is then Eiltered thus separating the . .
1~ ?YI
1 ammoni~m fluoride solution from the pr~cipitated niobium
2 hydroxide. The niobium hydroxide filter cake i5 then dried and
3 calcined at 875 to 1000C. to remove moisture and absorbed
4 ammonium fluoride. The ammonium fluoride solutions create a waste disposal problem and must be treated with lime to react 6 with the ammonium fluoride according to the reaction:
7 2NH4F + CaO > CaF2 + 2NH3 + H20 (I~
8 Generally, this reaction takes place in an ammonia stripping 9 column whereby the released ammonia is recovered in the overhead fraction.
11 The calcined Nb2O5 can then be alumino-thermically 12 reduced in the presence of an alloying element such as iron, 13 nickel, or chromium to produce a vacuum-grade niobium-containing 14 alloy.
It has now been found that by recovering niobium values 16 from aqueous hydrofluoric acid strip solutions which are evapo-1 rated to dryness following which the residue is baked at a ] temperature from about 150C. to 250C., niobium oxyfluoride 1 (NbO2F) is recovered which can be alumino-thermically reduced to a vacuum-grade alloy. The process is performed in a simple 2 efficient manner and avoids numerous disadvan~ages of the 2 prior art. In addition, about 1.5 pounds hydrogen fluoride 23 per pound of niobium is recovered in the process, 24 DESCRIPTION OF THE DRA~ING
The Figure of drawing illustrates a typical flow sheet in 26 the process for recovering niobium values, the process being par-27 ticularized in the Examples to follow.
28 DETAILED DE~CRIPTION OF T~E PREFERRED EMBODIMENT
29 Practice of the present invention provides an effective means by which niobium alloys may be produced by alumino-31 thermic reduction of niobium oxyfluoride, NbO2F) which may be 32 prepared by evaporating a hydrofluoric acid solution containin~
33 niobium values to dryness following which the dried residue is 34 baked for conversion to niobium oxyfluoride. Alternatively, 1 ~iobium oxyfluoride may be converted to niobiurn pentoxide, 2 Nb2O5, by calcining in the presence of water vapor.
3 In an embodiment of this invention, there is disclosed 4 the treatment of aqueous hydrofluoric acid soluticns of niobium emanating from the liquid-liquid extraction and purification 6 of niobium.
7 It has now been found that by the present invention 8 there is provided a method of recovering the niobium values from 9 an aqueous niobium fluoride solution,and at the same time recovering the hydrofluoric acid values from the solution. The 11 process involves evaporating an aqueous solution of niobium 12 fluoride from its initial concentration of about 70 to 140 grams 13 ~of niobium per liter to about 350 to 700 yrams of niobium per 14 ¦ liter in a closed evaporator attached to a condenser to recover 15 ¦ the vapors emanating from the evaporation. The condensed vapors 16 ¦ normally contain about 8 to 12% by weight hydrofluoric acid.
17 ¦ The concentrated niobium fluoride solution is then placed in a ~8 I.suitable tray, for example, nickel, and evaporated to dryness at 19¦¦ a temperature greater than 150C. The vapors from this evapora~
201 tion are also recovered as an approximate 50~ by ~eight hydro-2i¦ fluoric acid solution. The residue cake that remains in the tray 22 is niobium oxyfluoride (NbO2F). The recovered niobium oxyfluorid O
23 can be calcined in the presence of water vapor at about 500 to 24 ¦ 1000C. to form niobium pentoxide (Nb2O5) by the following reaction:
2~ 2 NbO2F + H2O ~ 2 5 HF
27 ~n advantage of this process is that silicon and 23 antimony, comrnon impurities in niobium pentoxide produced in ~
29 the customary way, are removed.
~0l ~acuum grade ferro-, nickel-, or chromium-niobium are 31¦ customarily produced from high purity niobium pentoxide (Nb2O5) which has been made by ammonia precipitation of a high purity niobium fluoride solution. The precipitate is filtered, washed, dried and calcined at about 1000C. The calcined niobium pentoxide is then mixed with aluminum powder and either iron, chromium or nickel powder, lime or fluorspar for fluxing and sodium chlorate as a heat booster. This mixture is ignited in a suitable container to produce the desired alloy by the alumino-thermic reaction:
3 Cb2O5 + 10 Al - ~ 6 Cb + 5 A12O3 (III) Now, however, it has been found that niobium oxyfluoride (NbO2F) can be used in place of niobium pentoxide for the alumino-thermic production of niobium alloys. The niobium oxyfluoride can be produced without the high temperature calcination step which is a source of contamination of the high purity niobium pentoxide. The fluorine content of the niobium ox-~fluoride passes into the slag where it acts as an efficient flux and assists in metal collection during the reduction step. In addition, the aluminum reduction of niobium oxyfluoride generates more exothermicity than the reduction of niobium pentoxide resulting in the elimination of a chemical heat booster such as sodium chlorate. The addition of lime (CaO) or the like in sufficient quantity to react approximately stoichiometrically with the fluorine in the niobium oxyfluoride (NbO2F~ is desirable and is found necessary. Without the lime addition, aluminum fluorides would be volatilized -thus agitating the molten system and, at the same time, removing heat and leaving a high melting point slag, A12O3.
The overall reaction for the reduction of niobium oxyfluoride with aluminum in the presence of lime follows:
(IV) 6 NbO2F + 10 Al -~ 3 CaO - ~ 6 Nb A 2 2 1 The reaction probably -takes place in two steps:
2 6 NbO2F ~- 10 Al > 6 Nb ~ 4 A123 + 2 AlF3 (V) 3 ~ F2000 = -468 Kcal.
4 and 2 AlF + 3 CaO -~ A12O + 3 CaF (VI) 6 ~ F2000 = -114 Kcal~
7 ~ F2000 (Overall) = -582 Kcal.
8 which can be contrasted to the Nb2O5 reaction:
9 3 Nb2O5 + 10 Al - ~ 6 Nb + 5 A12O3 (VII) ~ F2000 = -450 Kcal.
11 Thus, it can be seen that at thermite reaction temperatures the 12 free energy of reaction is about 29% greater for the NbO2F
13 system than the Nb2O5 system.
14 Of course, other oxides capable of reacting with aluminum fluoride at thermite temperatures can also be used in 16 place of calcium oxide. The list includes materials such as 17 strontium oxide, barium oxide, magnesium oxide, and lithium ~8 oxide as follows:
19 2 AlF3 + 3 SrO ~ A12O3 + 3 SrF2 (VIII) ~F = -150 Kcal 21 2 AlF3 + 3 BaO ~ A12O3 + 3 BaF2 (IX) 22¦ f~ F2000 = -156 Kcal.
23¦ 3 3 MgO ~ Al2O3 + 3 MgF2 (X) 24 ~ F = -69 Kcal 25 ¦ 3 3 Li2O ~ A123 + 6 LiF (XI) 26 ¦ ~ F - -177 Kcal 27 Typically, the reactions proceed using stoichiometri-28 cal amounts of reactants, and preferably a slight excess of the 29 oxides.
Thus, by the present process alloys such as ferro-31 niobium, nickel-niobium, or chromium-niobium can be effectively l6~
1 prepared by the alumino-thermic reduction of niobium oxyfluoride 2 without the use of a chemical or thermal heat booster.
3 The following examples illustrate practice of the 4 present invention in greater detail. In the examples, as well as in this specification generally, all parts and percentages 6 are given by weight unless indicated othe~wise.
8 A solution of niobium fluoride emanating from the 9 liquid-liquid extraction of niobium was found to contain:
10Nb =134.8 grams/liter 11HF =238 grams/liter 12F /Nb Mole~Ratio =8.2 13Antimony =500 ppm (Sb/Nb ~asis) 14Silicon =1200 ppm (Si/Nb Basis) About 3,100 gallons of this solution was e~aporated to 893 16 gallons. The boiling point at the end of the evaporation was 17 122C. The concentrated niobium solution was found to contain:
1~ Nb = 468 grams/liter 19 HF = 6~5 grams/liter F /Cb Mole Ratio = 6.2 2i The condensed vapors from the evaporation were 2 collected. The condensate consisted of 70 gallons of methyl-23 isobutylketone plus 2,400 gallons of hydrofluoric acid solution 2 containing 75 grams/liter HF. This amounts to a recovery of 2~ ¦ 0.43 lbs. 100% HF per pound of niobium in the original solution.
26 ¦ The concentrated niobium-bearing solution was found to 27 ¦ be stable with no crystallization or precipitation of solids on 28 prolonged storage at ambient conditions. A number of niobium-29 ¦ bearing solutions were evaporated to test the recovery of 3~ hydrof uoric acid and methylisob~ltylketone under varying . .. . .
1¦l concentrations of niobium. These are reported in Table I.
21~ TABLE I
3 CO~CENTRATION OF NIOBIUM-BEARING SOL~TIONS
.I
4¦ R~N NO. 1 2 3 4 5 51 Nb-Solution 61 ~b (gm/l.) 103.5 123 134 147 163 7~ HF lgm/l.) 223.5 227 237 252 263 81 F/Cb ~lole Ratio 10 8.55 8.2 7.95 752 9 I Condensate 10 ¦ ~vaporated 11 ~ (% by Wt.) 77.581.7 78.5 79.2 75.5 12 I HF (gm/l.) ~ 92.4 109.5 118 116 99.5 13 HF/Nb ~lb/lb) 0.68 0.71 0.67 0.61 0.45 14 MIBK/Nb(lb/lb) 0.17 0.10 0.12 0.09 0.08 Conc. Cb-Solution 16 Nb (gm/l.) 460 668 625 756 665 17 HF (gm/l.) 680 757 682 735 772 18 F/Cb ~ole l9 Ratio 6.855.27 5.06 4.5 5.4 The concentrated niobium-bearing solution was then 21 evaForated to dryness in a nickel tray contained in a carbon-22l llned externally heated oven maintained at 232C. The resulting 23 dry product was identified by X-ray diffraction to be NbO2F.
24 Analysis of the product was:
Ingredient Percent by Weight Impurity ppm 26 ~b = 61.95 Sb Basis) 27 I F = 13.8 Si = ~100 28~ As c~n. be seen, about 64~ by weight of the antimony and greater 29 than ~9i of the silicon were removed by the evaporation step.
301 .~ c aporated vapors from the oven vdried during the course of ~l ~7~
:
;~ 9 1 the evaporation from abou-t 15~ HF to greater than 90~ HF at the 2 end. secause of this variation in HF concentration, the use 3 ¦ of a contact condenser to recover the HF is impractical. A
4 ¦ Venturi-type scrubber which can quench and condense the
7 2NH4F + CaO > CaF2 + 2NH3 + H20 (I~
8 Generally, this reaction takes place in an ammonia stripping 9 column whereby the released ammonia is recovered in the overhead fraction.
11 The calcined Nb2O5 can then be alumino-thermically 12 reduced in the presence of an alloying element such as iron, 13 nickel, or chromium to produce a vacuum-grade niobium-containing 14 alloy.
It has now been found that by recovering niobium values 16 from aqueous hydrofluoric acid strip solutions which are evapo-1 rated to dryness following which the residue is baked at a ] temperature from about 150C. to 250C., niobium oxyfluoride 1 (NbO2F) is recovered which can be alumino-thermically reduced to a vacuum-grade alloy. The process is performed in a simple 2 efficient manner and avoids numerous disadvan~ages of the 2 prior art. In addition, about 1.5 pounds hydrogen fluoride 23 per pound of niobium is recovered in the process, 24 DESCRIPTION OF THE DRA~ING
The Figure of drawing illustrates a typical flow sheet in 26 the process for recovering niobium values, the process being par-27 ticularized in the Examples to follow.
28 DETAILED DE~CRIPTION OF T~E PREFERRED EMBODIMENT
29 Practice of the present invention provides an effective means by which niobium alloys may be produced by alumino-31 thermic reduction of niobium oxyfluoride, NbO2F) which may be 32 prepared by evaporating a hydrofluoric acid solution containin~
33 niobium values to dryness following which the dried residue is 34 baked for conversion to niobium oxyfluoride. Alternatively, 1 ~iobium oxyfluoride may be converted to niobiurn pentoxide, 2 Nb2O5, by calcining in the presence of water vapor.
3 In an embodiment of this invention, there is disclosed 4 the treatment of aqueous hydrofluoric acid soluticns of niobium emanating from the liquid-liquid extraction and purification 6 of niobium.
7 It has now been found that by the present invention 8 there is provided a method of recovering the niobium values from 9 an aqueous niobium fluoride solution,and at the same time recovering the hydrofluoric acid values from the solution. The 11 process involves evaporating an aqueous solution of niobium 12 fluoride from its initial concentration of about 70 to 140 grams 13 ~of niobium per liter to about 350 to 700 yrams of niobium per 14 ¦ liter in a closed evaporator attached to a condenser to recover 15 ¦ the vapors emanating from the evaporation. The condensed vapors 16 ¦ normally contain about 8 to 12% by weight hydrofluoric acid.
17 ¦ The concentrated niobium fluoride solution is then placed in a ~8 I.suitable tray, for example, nickel, and evaporated to dryness at 19¦¦ a temperature greater than 150C. The vapors from this evapora~
201 tion are also recovered as an approximate 50~ by ~eight hydro-2i¦ fluoric acid solution. The residue cake that remains in the tray 22 is niobium oxyfluoride (NbO2F). The recovered niobium oxyfluorid O
23 can be calcined in the presence of water vapor at about 500 to 24 ¦ 1000C. to form niobium pentoxide (Nb2O5) by the following reaction:
2~ 2 NbO2F + H2O ~ 2 5 HF
27 ~n advantage of this process is that silicon and 23 antimony, comrnon impurities in niobium pentoxide produced in ~
29 the customary way, are removed.
~0l ~acuum grade ferro-, nickel-, or chromium-niobium are 31¦ customarily produced from high purity niobium pentoxide (Nb2O5) which has been made by ammonia precipitation of a high purity niobium fluoride solution. The precipitate is filtered, washed, dried and calcined at about 1000C. The calcined niobium pentoxide is then mixed with aluminum powder and either iron, chromium or nickel powder, lime or fluorspar for fluxing and sodium chlorate as a heat booster. This mixture is ignited in a suitable container to produce the desired alloy by the alumino-thermic reaction:
3 Cb2O5 + 10 Al - ~ 6 Cb + 5 A12O3 (III) Now, however, it has been found that niobium oxyfluoride (NbO2F) can be used in place of niobium pentoxide for the alumino-thermic production of niobium alloys. The niobium oxyfluoride can be produced without the high temperature calcination step which is a source of contamination of the high purity niobium pentoxide. The fluorine content of the niobium ox-~fluoride passes into the slag where it acts as an efficient flux and assists in metal collection during the reduction step. In addition, the aluminum reduction of niobium oxyfluoride generates more exothermicity than the reduction of niobium pentoxide resulting in the elimination of a chemical heat booster such as sodium chlorate. The addition of lime (CaO) or the like in sufficient quantity to react approximately stoichiometrically with the fluorine in the niobium oxyfluoride (NbO2F~ is desirable and is found necessary. Without the lime addition, aluminum fluorides would be volatilized -thus agitating the molten system and, at the same time, removing heat and leaving a high melting point slag, A12O3.
The overall reaction for the reduction of niobium oxyfluoride with aluminum in the presence of lime follows:
(IV) 6 NbO2F + 10 Al -~ 3 CaO - ~ 6 Nb A 2 2 1 The reaction probably -takes place in two steps:
2 6 NbO2F ~- 10 Al > 6 Nb ~ 4 A123 + 2 AlF3 (V) 3 ~ F2000 = -468 Kcal.
4 and 2 AlF + 3 CaO -~ A12O + 3 CaF (VI) 6 ~ F2000 = -114 Kcal~
7 ~ F2000 (Overall) = -582 Kcal.
8 which can be contrasted to the Nb2O5 reaction:
9 3 Nb2O5 + 10 Al - ~ 6 Nb + 5 A12O3 (VII) ~ F2000 = -450 Kcal.
11 Thus, it can be seen that at thermite reaction temperatures the 12 free energy of reaction is about 29% greater for the NbO2F
13 system than the Nb2O5 system.
14 Of course, other oxides capable of reacting with aluminum fluoride at thermite temperatures can also be used in 16 place of calcium oxide. The list includes materials such as 17 strontium oxide, barium oxide, magnesium oxide, and lithium ~8 oxide as follows:
19 2 AlF3 + 3 SrO ~ A12O3 + 3 SrF2 (VIII) ~F = -150 Kcal 21 2 AlF3 + 3 BaO ~ A12O3 + 3 BaF2 (IX) 22¦ f~ F2000 = -156 Kcal.
23¦ 3 3 MgO ~ Al2O3 + 3 MgF2 (X) 24 ~ F = -69 Kcal 25 ¦ 3 3 Li2O ~ A123 + 6 LiF (XI) 26 ¦ ~ F - -177 Kcal 27 Typically, the reactions proceed using stoichiometri-28 cal amounts of reactants, and preferably a slight excess of the 29 oxides.
Thus, by the present process alloys such as ferro-31 niobium, nickel-niobium, or chromium-niobium can be effectively l6~
1 prepared by the alumino-thermic reduction of niobium oxyfluoride 2 without the use of a chemical or thermal heat booster.
3 The following examples illustrate practice of the 4 present invention in greater detail. In the examples, as well as in this specification generally, all parts and percentages 6 are given by weight unless indicated othe~wise.
8 A solution of niobium fluoride emanating from the 9 liquid-liquid extraction of niobium was found to contain:
10Nb =134.8 grams/liter 11HF =238 grams/liter 12F /Nb Mole~Ratio =8.2 13Antimony =500 ppm (Sb/Nb ~asis) 14Silicon =1200 ppm (Si/Nb Basis) About 3,100 gallons of this solution was e~aporated to 893 16 gallons. The boiling point at the end of the evaporation was 17 122C. The concentrated niobium solution was found to contain:
1~ Nb = 468 grams/liter 19 HF = 6~5 grams/liter F /Cb Mole Ratio = 6.2 2i The condensed vapors from the evaporation were 2 collected. The condensate consisted of 70 gallons of methyl-23 isobutylketone plus 2,400 gallons of hydrofluoric acid solution 2 containing 75 grams/liter HF. This amounts to a recovery of 2~ ¦ 0.43 lbs. 100% HF per pound of niobium in the original solution.
26 ¦ The concentrated niobium-bearing solution was found to 27 ¦ be stable with no crystallization or precipitation of solids on 28 prolonged storage at ambient conditions. A number of niobium-29 ¦ bearing solutions were evaporated to test the recovery of 3~ hydrof uoric acid and methylisob~ltylketone under varying . .. . .
1¦l concentrations of niobium. These are reported in Table I.
21~ TABLE I
3 CO~CENTRATION OF NIOBIUM-BEARING SOL~TIONS
.I
4¦ R~N NO. 1 2 3 4 5 51 Nb-Solution 61 ~b (gm/l.) 103.5 123 134 147 163 7~ HF lgm/l.) 223.5 227 237 252 263 81 F/Cb ~lole Ratio 10 8.55 8.2 7.95 752 9 I Condensate 10 ¦ ~vaporated 11 ~ (% by Wt.) 77.581.7 78.5 79.2 75.5 12 I HF (gm/l.) ~ 92.4 109.5 118 116 99.5 13 HF/Nb ~lb/lb) 0.68 0.71 0.67 0.61 0.45 14 MIBK/Nb(lb/lb) 0.17 0.10 0.12 0.09 0.08 Conc. Cb-Solution 16 Nb (gm/l.) 460 668 625 756 665 17 HF (gm/l.) 680 757 682 735 772 18 F/Cb ~ole l9 Ratio 6.855.27 5.06 4.5 5.4 The concentrated niobium-bearing solution was then 21 evaForated to dryness in a nickel tray contained in a carbon-22l llned externally heated oven maintained at 232C. The resulting 23 dry product was identified by X-ray diffraction to be NbO2F.
24 Analysis of the product was:
Ingredient Percent by Weight Impurity ppm 26 ~b = 61.95 Sb Basis) 27 I F = 13.8 Si = ~100 28~ As c~n. be seen, about 64~ by weight of the antimony and greater 29 than ~9i of the silicon were removed by the evaporation step.
301 .~ c aporated vapors from the oven vdried during the course of ~l ~7~
:
;~ 9 1 the evaporation from abou-t 15~ HF to greater than 90~ HF at the 2 end. secause of this variation in HF concentration, the use 3 ¦ of a contact condenser to recover the HF is impractical. A
4 ¦ Venturi-type scrubber which can quench and condense the
5 ¦ evolved vapors is preferred although an absorption tower could
6 ¦ also be used. The recovered HF solution averages about 50% HF.
7 ¦ An example of the above data is shown in a typical
8 ¦ process flow sheet, shown in the drawing. Thus, 2,057 gallons
9 ¦ of niobium solu-tion having 140 gram/liter of Nb values and 240 iO ¦ grams/liter of HF are evaporated, the overhead condensate being 11 ¦ composed of 41 gallons MIBK and about 1400 gallons of HF solu-12 ¦ tion. The concentrate Nb solution is 588 gallons which is baked 13 ¦ in an oven to yield 3717 pounds of NbO2F. Vapors recovered from 14 ¦ a Venturi scrubber yield 2577 pounds HF and 2696 pounds of water, 15 ¦ i.e., approximately 49% by weight HF solution.
16 ¦ EXAMPI,E 2 17 A number of evaporations to dryness were made to 18 determine the temperature re~uired for optimum conversion to 19 NbO2F. These results are shown in Table II. The data show a lower fluorine content in the NbO2F with increasing temperature.
Zl For this set of experiments a contact condenser was used to 2 recover the HF solution and an indeterminant amount of HF was 23 lost to the atmosphere. If the NbO2F product is to be calcined to Nb2O5, an even lower temperature can be used. For example, 25 ¦ in one experiment at 125C. the product contained 15.8~ F but 26 ¦ also still contained water which, of course, would be removed - 27 ¦ by calcination. The absorbed water would, however, be counter-28 ¦ productive if the NbO2F were to be used directly in alumino-29 ¦ thermic reactions.
1 3L~
2 EVAPORATION OF CONCENTR~'rED COLUMBIUM-BE~RING SOLUTIO~IS
3 RUN NO.
Evaporation Temp. C. 204 218 232 232 6 Charge 7 Gallons 4.5 4.634.5 6.75 8 Pounds 66.4 66.063.5 93.3 9 Pounds Niobium 19.4 18.217.1 24.6
16 ¦ EXAMPI,E 2 17 A number of evaporations to dryness were made to 18 determine the temperature re~uired for optimum conversion to 19 NbO2F. These results are shown in Table II. The data show a lower fluorine content in the NbO2F with increasing temperature.
Zl For this set of experiments a contact condenser was used to 2 recover the HF solution and an indeterminant amount of HF was 23 lost to the atmosphere. If the NbO2F product is to be calcined to Nb2O5, an even lower temperature can be used. For example, 25 ¦ in one experiment at 125C. the product contained 15.8~ F but 26 ¦ also still contained water which, of course, would be removed - 27 ¦ by calcination. The absorbed water would, however, be counter-28 ¦ productive if the NbO2F were to be used directly in alumino-29 ¦ thermic reactions.
1 3L~
2 EVAPORATION OF CONCENTR~'rED COLUMBIUM-BE~RING SOLUTIO~IS
3 RUN NO.
Evaporation Temp. C. 204 218 232 232 6 Charge 7 Gallons 4.5 4.634.5 6.75 8 Pounds 66.4 66.063.5 93.3 9 Pounds Niobium 19.4 18.217.1 24.6
10 Pounds HF 25.1 23.421.6 28.7
11 Condensate
12 Gallons 2.98 3.423.29 4.67
13 Pounds 29.3 33.031.5 45.2
14 Pounds HF 14.7 14.712.2 18.7
15¦ Pounds HF/Pound Nb 0.76 0.810.71 0.76
16 ¦ HF Concentration, % by Wt. 50.2 44.3 38.8 41.3
17 ¦ Solid Residue )8 ¦ Pounds 30.6 30.329.0 41.6 19 F (% by Wt.) 15.9 15.0410.23 11.41 Niobium (% by Wt.) 61.6 64.362.3 62.1 2i X-Ray Identification CbO2F CbO2F CbO2F CbO2F
23 A number of corrosion tests were made to determine 24 acceptable tray materials. In general, nickel and nickel-containing alloys sueh as Monel and Hastelloy A, B, and C were 26 found to be satisfaetory.
27 A portion of the NbO2F was calcined at 1000C. in the 28 presence of water vapor and was converted to Nb2O5 aeeording to 29 the reaction:
2 NbO2F + H2() - ~ Nb25 ~: i 1 ~ EXAMPLE 4 2 A quantity of NbO2F that had been produced at 232C.
3 and which contained 62.1~ Nb was crushed to 8 mesh by down and 4 blended with aluminum powder, iron powder, lime and sodium chlorate. Three small scale reactions were made varying the 6 amount of aluminum from 90% to 110% by weight of the amount stoi-7 chiometrically required to react with the CbO2F and the sodium 8 chlorate. These results are given in Table III.
10 ¦ SMALL-SCALE ALUMINO-THERMIC REDUCTIONS
11 ¦ Run No. 1 2 3 12 ¦ Wt. Reagents, grams 13 ¦ NbO2F 980 980 980 14 ¦ Iron Powder 330 330 330 15 ¦ Aluminum Powder 291 321 351 16 l Sodium Chlorate 50 50 50 17 l Lime, CaO 170 170 170 ~8 ¦ Total 1821 1851 1881 19 ~ Aluminum Stoichiometry 90 100 110 20 ~ Wt. Alloy, grams 695 686 705 2i ¦ Alloy Analysis 22 ~ Nb 58.2 59.9 58.1 23 % Al 0.64 1.02 4.0 24 ppm 2 1470 1265 750 ppm N2 450 540 470 2 These results indicate that an excess amount of 2 aluminum is no-t re~uired. The ignition and firing proceeded 2 smoothly with very li~tle splashing. Due to the small scale - 2 of the reactions, the molten charge cooled rapidly precluding 3 complete metal collection. This phenomenon is typical of all 1 small scale thermite reactions. Excellerlt slag-metal separation 2 was observedA
4 A second set of experiments was designed to determine if lime was necessary for the reaction. The same NbO2F was used 6 as the previous set of experiments of Example 4 and aluminum 7 stoichiometry was maintained at 100%. These results are shown 8 in Table IV.
10CaO-FREE THERMITE REDUCTIONS OF NbO2F
11 Charge, Grams 1 2 3 12 NbO2F 980 ~80 980 13 Fe Powder 330 330 330 14 Al Powder 296 321 331 NaClO3 0 50 70 16 Total 1606 1681 1711 17 Slag Condition Thick Thick Thick
23 A number of corrosion tests were made to determine 24 acceptable tray materials. In general, nickel and nickel-containing alloys sueh as Monel and Hastelloy A, B, and C were 26 found to be satisfaetory.
27 A portion of the NbO2F was calcined at 1000C. in the 28 presence of water vapor and was converted to Nb2O5 aeeording to 29 the reaction:
2 NbO2F + H2() - ~ Nb25 ~: i 1 ~ EXAMPLE 4 2 A quantity of NbO2F that had been produced at 232C.
3 and which contained 62.1~ Nb was crushed to 8 mesh by down and 4 blended with aluminum powder, iron powder, lime and sodium chlorate. Three small scale reactions were made varying the 6 amount of aluminum from 90% to 110% by weight of the amount stoi-7 chiometrically required to react with the CbO2F and the sodium 8 chlorate. These results are given in Table III.
10 ¦ SMALL-SCALE ALUMINO-THERMIC REDUCTIONS
11 ¦ Run No. 1 2 3 12 ¦ Wt. Reagents, grams 13 ¦ NbO2F 980 980 980 14 ¦ Iron Powder 330 330 330 15 ¦ Aluminum Powder 291 321 351 16 l Sodium Chlorate 50 50 50 17 l Lime, CaO 170 170 170 ~8 ¦ Total 1821 1851 1881 19 ~ Aluminum Stoichiometry 90 100 110 20 ~ Wt. Alloy, grams 695 686 705 2i ¦ Alloy Analysis 22 ~ Nb 58.2 59.9 58.1 23 % Al 0.64 1.02 4.0 24 ppm 2 1470 1265 750 ppm N2 450 540 470 2 These results indicate that an excess amount of 2 aluminum is no-t re~uired. The ignition and firing proceeded 2 smoothly with very li~tle splashing. Due to the small scale - 2 of the reactions, the molten charge cooled rapidly precluding 3 complete metal collection. This phenomenon is typical of all 1 small scale thermite reactions. Excellerlt slag-metal separation 2 was observedA
4 A second set of experiments was designed to determine if lime was necessary for the reaction. The same NbO2F was used 6 as the previous set of experiments of Example 4 and aluminum 7 stoichiometry was maintained at 100%. These results are shown 8 in Table IV.
10CaO-FREE THERMITE REDUCTIONS OF NbO2F
11 Charge, Grams 1 2 3 12 NbO2F 980 ~80 980 13 Fe Powder 330 330 330 14 Al Powder 296 321 331 NaClO3 0 50 70 16 Total 1606 1681 1711 17 Slag Condition Thick Thick Thick
18 Firing Time, Seconds 75 40 30
19 Firing Conditions Very Smoky Very Smoky Very Smoky
20 Metal Collection None None None 1 21 Conclusions drawn from this set of experiments were 22 that during the reaction aluminum fluoride is volatilized and 23 does not furnish a slagging effect. The use of lime in 24 approximately stoichiometric quantity to the fluorine contained in the system is recommended.
27 In another set of experiments, the reaction of NbO2F
28 was compared to Nb2O5 on a 63 lb. niobium scale. These results 29 are shown in Table V.
L~
1 T~BLE V
2 COMPARISON OF NbO2F AND Nb2O5 3 Mix 1 Mix 2 4 NbO2F, lbs.100 ~63 lb. Cb~ -Nb2O5, lbs. - 90 (63 lb. Cb) 6 Al Powder 32 38.4 7 CaO 17 17 8 NaClO3 - 16 9 Fe Powder 26.9 26.9 Total, lbs. 175.9 188.3 11 Wt. Alloy, lbs. 81.5 80.0 12 ~ Nb 66.7 67.5 13 % Nb Recovery 86.3 85.7 14 The results of Table V show that, indeed, NbO2F can be alumino-thermically reduced to ferro-columbium without a 16 heat booster. Niobium recoveries were comparable with those from 17 Nb2O5.
19 The process of Example 6 was further scaled up to a 350 lb. niobium contained set of reactions. These results are 2i ¦ shown in Table VI.
22 ¦ TABLE VI
23 ¦ COMPARISON OF NbO2F and Nb2_5 ON A 350 LB. NIOBIUM SCALE
24 NbO2F -2-5 25 ¦ NbO2F, lbs. 565 (350 lb. Cb) 26 ¦ 2 5 500 (350 lb. Nb) 27 ¦ Fe Powder 169 170 28 ¦ Al Powder 172 193 29 ¦ CaO 115 30 ¦ CaF2 - 100 31 MaClO3 - 42 32 Total, lbs. 1021 1005 1 T~BL~ VI (CONT.) .
2 NbO2F Nb25 3 Wt. Alloy, lbs. 493 490 4 % Nb 64.4 65.0 % Nb Recovery 90.7 91.0 6 These results of Table VI show comparable recoveries. It will 7 be noted that the Nb205 required 21 lbs. more aluminum to react 8 with the 42 lbs. NaClO3 added as a heat booster. The NbO2F
9 reaction proceeded mildly with reduced fume emission. The slag, weighing 531 lbs., contained 13.6% fluorine for a 92.6 11 fluorine retention in the slag. The results show that NbO2F
12 can be used for the preparation of ferro-, nickel-, or 13 chromium-columbium provided lime is added to the mix to react 14 with essentially all of the fluorine introduced in the NbO2F.
From the foregoing, it will be readily apparent to 16 those skilled in the art that various modifications and changes 17 may be effected without departing from practice of the presently ~8 disclosed invention. An example of such a modification would be 19 to introduce iron oxide, chromium oxide or nickel oxide instead of the metallic elements into the mix. Under these conditions
27 In another set of experiments, the reaction of NbO2F
28 was compared to Nb2O5 on a 63 lb. niobium scale. These results 29 are shown in Table V.
L~
1 T~BLE V
2 COMPARISON OF NbO2F AND Nb2O5 3 Mix 1 Mix 2 4 NbO2F, lbs.100 ~63 lb. Cb~ -Nb2O5, lbs. - 90 (63 lb. Cb) 6 Al Powder 32 38.4 7 CaO 17 17 8 NaClO3 - 16 9 Fe Powder 26.9 26.9 Total, lbs. 175.9 188.3 11 Wt. Alloy, lbs. 81.5 80.0 12 ~ Nb 66.7 67.5 13 % Nb Recovery 86.3 85.7 14 The results of Table V show that, indeed, NbO2F can be alumino-thermically reduced to ferro-columbium without a 16 heat booster. Niobium recoveries were comparable with those from 17 Nb2O5.
19 The process of Example 6 was further scaled up to a 350 lb. niobium contained set of reactions. These results are 2i ¦ shown in Table VI.
22 ¦ TABLE VI
23 ¦ COMPARISON OF NbO2F and Nb2_5 ON A 350 LB. NIOBIUM SCALE
24 NbO2F -2-5 25 ¦ NbO2F, lbs. 565 (350 lb. Cb) 26 ¦ 2 5 500 (350 lb. Nb) 27 ¦ Fe Powder 169 170 28 ¦ Al Powder 172 193 29 ¦ CaO 115 30 ¦ CaF2 - 100 31 MaClO3 - 42 32 Total, lbs. 1021 1005 1 T~BL~ VI (CONT.) .
2 NbO2F Nb25 3 Wt. Alloy, lbs. 493 490 4 % Nb 64.4 65.0 % Nb Recovery 90.7 91.0 6 These results of Table VI show comparable recoveries. It will 7 be noted that the Nb205 required 21 lbs. more aluminum to react 8 with the 42 lbs. NaClO3 added as a heat booster. The NbO2F
9 reaction proceeded mildly with reduced fume emission. The slag, weighing 531 lbs., contained 13.6% fluorine for a 92.6 11 fluorine retention in the slag. The results show that NbO2F
12 can be used for the preparation of ferro-, nickel-, or 13 chromium-columbium provided lime is added to the mix to react 14 with essentially all of the fluorine introduced in the NbO2F.
From the foregoing, it will be readily apparent to 16 those skilled in the art that various modifications and changes 17 may be effected without departing from practice of the presently ~8 disclosed invention. An example of such a modification would be 19 to introduce iron oxide, chromium oxide or nickel oxide instead of the metallic elements into the mix. Under these conditions
21 aluminum would preferentially reduce the metallic oxides and the 2 resulting metals would be available to alloy with the niobium 24 as reaction proceeded.
Claims (9)
1. A process which comprises reducing niobium oxy-fluoride in the presence of iron, chromium or nickel with aluminum and recovering the resulting niobium alloys.
2. The process according to claim 1 wherein iron, chromium, and nickel are present as the oxides thereof.
3. The process according to claim 1 wherein lime is introduced in the mix in sufficient quantity to react with essentially all of the fluorine contained in the niobium oxyfluoride.
4. The process according to claim 1 wherein oxides of calcium, strontium, barium, magnesium and lithium are added to react with essentially all the fluorine contained in the niobium oxyfluoride.
5. The process according to claim 1 wherein ferro-, nickel- or chromium-niobium are produced by aluminothermic reaction from niobium oxyfluoride without the addition of a thermal or chemical heat booster.
6. The process of claim 1 wherein the niobium oxy-fluoride is recovered from a hydrofluoric acid solution which comprises evaporating a niobium-bearing solution to dryness at a finishing temperature of greater than about 150°C., and recovering evaporated hydrofluoric acid by condensation or scrubbing.
7. The process according to claim 6 in which the niobium-bearing solution is first concentrated to 350-700 grams per liter niobium prior to evaporation to dryness.
8. The process according to claim 6 in which the evaporating tray is nickel or a nickel alloy.
9. The process according to claim 6 whereby anti-mony and silicon are removed from a niobium-bearing fluo-ride solution emanating from the recovery and purification of niobium by a liquid-liquid extraction.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US901,069 | 1978-04-28 | ||
| US05/901,069 US4164417A (en) | 1978-04-28 | 1978-04-28 | Process for recovery of niobium values for use in preparing niobium alloy products |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1116409A true CA1116409A (en) | 1982-01-19 |
Family
ID=25413556
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000324930A Expired CA1116409A (en) | 1978-04-28 | 1979-04-05 | Process for recovery of niobium values for use in preparing niobium alloy products |
Country Status (10)
| Country | Link |
|---|---|
| US (1) | US4164417A (en) |
| JP (1) | JPS6027742B2 (en) |
| BE (1) | BE875936A (en) |
| BR (1) | BR7902578A (en) |
| CA (1) | CA1116409A (en) |
| DD (1) | DD144076A5 (en) |
| DE (1) | DE2917084A1 (en) |
| FR (1) | FR2424326A1 (en) |
| NL (1) | NL7903207A (en) |
| SU (1) | SU1041037A3 (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2927835A1 (en) * | 1979-07-10 | 1981-06-04 | Hermann C. Starck Berlin, 1000 Berlin | METHOD FOR RECOVERY OF HYDROFLUORIC ACID AND DEPOSITABLE RESIDUES IN THE PROCESSING OF RAW MATERIALS CONTAINING NIOBE AND / OR TANTALY |
| DE3017782C2 (en) * | 1980-05-09 | 1982-09-30 | Th. Goldschmidt Ag, 4300 Essen | Process for the production of sinterable alloy powders based on titanium |
| JPS62216603A (en) * | 1986-03-17 | 1987-09-24 | Agency Of Ind Science & Technol | Automatic solvent extractor for analyzing trace element in water |
| WO1989001914A1 (en) * | 1987-08-27 | 1989-03-09 | Hughes Aircraft Company | PROCESS FOR PURIFYING (Nb1-xTax)2O5 AND THE PREPARATION OF KNb1-xTaxO3-CRYSTALS THEREFROM |
| US5437848A (en) * | 1992-07-10 | 1995-08-01 | Cabot Corporation | Recovery of metal values from process residues |
| AU2581797A (en) * | 1996-03-26 | 1997-10-17 | Cabot Corporation | Method for solubilizing metal values from ta-nb-ore materials containing insoluble fluorides |
| US6843970B1 (en) | 1996-03-26 | 2005-01-18 | Cabot Corporation | Process for recovering metal values by dissolving them in a sulfuric acid solution containing a carbon source and a reducing agent |
| US7282187B1 (en) | 1996-03-26 | 2007-10-16 | Caboi Corporation | Recovery of metal values |
| WO2003055805A1 (en) * | 2001-12-27 | 2003-07-10 | Mitsui Mining & Smelting Co.,Ltd. | Powder of tantalum oxide or niobium oxide, and method for production thereof |
| KR20040091071A (en) * | 2002-02-27 | 2004-10-27 | 스텔라 케미파 가부시키가이샤 | Purification method for producing high purity niobium compound and/or tantalum compound |
| KR20040093062A (en) * | 2002-02-27 | 2004-11-04 | 스텔라 케미파 가부시키가이샤 | Purification method for producing high purity niobium compound and/or tantalum compound |
| RU2624562C1 (en) * | 2016-09-28 | 2017-07-04 | Общество с ограниченной ответственностью "МЕТСИНТЕЗ" | METHOD OF PRODUCING BILLETS FROM ALLOYS BASED ON INTERMETALLIDES OF Nb-Al SYSTEM |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR811117A (en) * | 1935-09-13 | 1937-04-07 | Metallurg De Hoboken Soc Gen | Process for extracting tantalum and niobium from metallurgical ores or by-products |
| FR810544A (en) * | 1935-09-13 | 1937-03-23 | Metallurg De Hoboken Soc Gen | Process for treating ores, metallurgical by-products or other raw materials containing tantalum and niobium |
| FR826114A (en) * | 1937-03-19 | 1938-03-23 | Metallurg De Hoboken Soc Gen | Improvements in the processing of materials containing tantalum or niobium, or tantalum and niobium |
| FR834449A (en) * | 1937-03-22 | 1938-11-21 | Metallurg De Hoboken Soc Gen | Improvements in processes for treating materials containing tantalum or niobium |
| US2905548A (en) * | 1957-09-06 | 1959-09-22 | Fansteel Metallurgical Corp | Method of recovering tantalum and columbium |
| US2953453A (en) * | 1958-06-20 | 1960-09-20 | Nat Distillers Chem Corp | Recovery of columbium values |
| US3523128A (en) * | 1968-06-17 | 1970-08-04 | Kawecki Chem Co | Production of concentrated aqueous tantalum oxalate solution |
| US3597192A (en) * | 1968-12-05 | 1971-08-03 | Atomic Energy Commission | Preparation of tantalum metal |
| US3712939A (en) * | 1971-03-29 | 1973-01-23 | Union Carbide Corp | Method for recovering tantalum and/or columbium |
-
1978
- 1978-04-28 US US05/901,069 patent/US4164417A/en not_active Expired - Lifetime
-
1979
- 1979-04-05 CA CA000324930A patent/CA1116409A/en not_active Expired
- 1979-04-24 NL NL7903207A patent/NL7903207A/en not_active Application Discontinuation
- 1979-04-26 BR BR7902578A patent/BR7902578A/en unknown
- 1979-04-27 FR FR7910890A patent/FR2424326A1/en active Pending
- 1979-04-27 DD DD79212569A patent/DD144076A5/en unknown
- 1979-04-27 SU SU792764201A patent/SU1041037A3/en active
- 1979-04-27 BE BE0/194905A patent/BE875936A/en not_active IP Right Cessation
- 1979-04-27 DE DE19792917084 patent/DE2917084A1/en not_active Withdrawn
- 1979-04-28 JP JP54052063A patent/JPS6027742B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6027742B2 (en) | 1985-07-01 |
| FR2424326A1 (en) | 1979-11-23 |
| BE875936A (en) | 1979-10-29 |
| NL7903207A (en) | 1979-10-30 |
| SU1041037A3 (en) | 1983-09-07 |
| DD144076A5 (en) | 1980-09-24 |
| JPS54145317A (en) | 1979-11-13 |
| DE2917084A1 (en) | 1979-11-08 |
| US4164417A (en) | 1979-08-14 |
| BR7902578A (en) | 1979-11-20 |
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